Lactose, is the naturally-occurring sugar in milk.
There are many natural sugars – like glucose, fructose and sucrose – and these sugars are found widely in nature; from fruits, vegetables and grains to honey and maple sap. But lactose? It’s almost non-existent in nature outside the milk of mammals – humans, cows, goats and sheep alike.
Lactose is composed of glucose and galactose, two simpler sugars used as energy directly by our body. Lactase, an enzyme, splits lactose into glucose and galactose. According to more recent studies, lactose may play a role in the absorption of calcium and other minerals such as copper and zinc, especially during infancy. Moreover, if it is not digested in the small intestine, lactose may be used by the intestinal microbiota (the microorganism population that lives in the digestive tract) as a nutrient (prebiotic). Lactose and other milk sugars also promote the growth of bifidobacteria in the gut and may play a life-long role in countering the aging-associated decline of some immune functions.
When we drink milk or have a milk-based product, lactase in our small intestines breaks down the milk sugar. It then gets absorbed into the body through the small intestines.
But people who are lactose intolerant don’t have it so easy. In them, the lactose doesn’t get broken down. Instead, it goes on to the colon, where it mixes with normal bacteria and ferments. It can cause things like gas, bloating and diarrhea.
Thankfully, there are many lactose free milk and dairy products to choose from. Like regular milk, lactose-free milk is a good source of protein, calcium, phosphorus, vitamin B12, riboflavin and vitamin D.
Helpful Links:
https://daa.asn.au/smart-eating-for-you/smart-eating-fast-facts/food-and-food-products/which-type-of-milk-should-i-drink/